Periyanan Vaduganathan

Dobutamine Echocardiography and Quantitative Rest-Redistribution 201Tl Tomography in Myocardial Hibernation Relation of Contractile Reserve to 201Tl Uptake and Comparative Prediction of Recovery of Function

BACKGROUND The purposes of this study were to evaluate the comparative accuracy of dobutamine echocardiography and quantitative rest-redistribution 201Tl tomography in the prediction of recovery of function after revascularization and to assess the relation of contractile reserve to thallium uptake. METHODS AND RESULTS Thirty-four patients with stable coronary disease and regional dysfunction underwent dobutamine echocardiography (2.5 up to 40 micrograms.kg-1.min-1) and rest-redistribution 201Tl tomography 1 day before revascularization. Resting echocardiography and scintigraphy were repeated at > or = 6 weeks. Before revascularization, resting 201Tl uptake was similar in segments demonstrating biphasic or sustained improvement and was higher than in those exhibiting no change or worsening function during dobutamine. After revascularization, 201Tl uptake increased only in segments that showed a biphasic response (from 66 +/- 12% to 78 +/- 13%; P < .05). Biphasic response had a sensitivity of 74% and specificity of 89% for prediction of recovery. The use of biphasic or sustained improvement responses increased the sensitivity to 86% with a decrease in specificity to 68%. Qualitative thallium assessment provided a high sensitivity (98%) but poor specificity (27%). Quantification of thallium uptake, however, improved its accuracy: a maximal uptake (at rest or redistribution) of > or = 60% yielded a 90% sensitivity and a 56% specificity. CONCLUSIONS In patients with myocardial hibernation, biphasic response during dobutamine is less sensitive but more specific for recovery of function, whereas indexes of 201Tl scintigraphy are in general more sensitive and less specific, the least accurate being a qualitative assessment of thallium uptake. The sensitivity and specificity of both methods, however, can be altered depending on the quantitative criteria of thallium uptake or combination of responses of the myocardium to dobutamine.

Identification of Hibernating Myocardium: Comparative Accuracy of Myocardial Contrast Echocardiography, Rest-Redistribution Thallium-201 Tomography and Dobutamine Echocardiography

OBJECTIVES We sought to evaluate the comparative accuracy of myocardial contrast echocardiography (MCE), quantitative rest-redistribution thallium-201 (Tl-201) tomography and low and high dose (up to 40 microg/kg body weight per min) dobutamine echocardiography (DE) in identifying myocardial hibernation. BACKGROUND Myocardial contrast echocardiography can assess myocardial perfusion and may therefore be useful in predicting myocardial hibernation. However, its accuracy in comparison to myocardial perfusion scintigraphy and to that of high dose DE remains to be investigated. METHODS Eighteen patients (aged [+/- SD] 57 +/- 10 years) with stable coronary artery disease and ventricular dysfunction underwent the above three modalities before coronary revascularization. Myocardial contrast echocardiography was achieved with intracoronary Albunex. Rest echocardiographic and Tl-201 studies were repeated > or = 6 weeks after revascularization. RESULTS Of 109 revascularized segments with severe dysfunction, 46 (42%) improved. Left ventricular ejection fraction increased from 38 +/- 14% to 45 +/- 13% at follow-up (p = 0.003). Rest Tl-201 uptake and the ratio of peak contrast intensity of dysfunctional to normal segments with MCE were higher (p < 0.01) in segments that recovered function compared with those that did not. Myocardial contrast echocardiography, thallium scintigraphy and any contractile reserve during DE had a similar sensitivity (89% to 91%) with a lower specificity (43% to 66%) for recovery of function. A biphasic response during DE was the most specific (83%) and the least sensitive (68%) (p < 0.01). The best concordance with MCE was Tl-201 (80%, kappa 0.57). Changes in ejection fraction after revascularization related significantly to the number of viable dysfunctional segments by all modalities (r = 0.54 to 0.65). CONCLUSIONS In myocardial hibernation, methods evaluating rest perfusion (MCE, Tl-201) or any contractile reserve have a similar high sensitivity but a low specificity for predicting recovery of function. A limited contractile reserve (biphasic response) increases the specificity of DE. Importantly, the three techniques identified all patients who had significant improvement in global ventricular function.

Evaluation of left ventricular wall motion, volumes, and ejection fraction by gated myocardial tomography with technetium 99m-labeled tetrofosmin: A comparison with cine magnetic resonance imaging

BackgroundWhether left ventricular function can be assessed accurately by gated single photon emission computed tomography (SPECT) in patients with myocardial infarction and severe perfusion defects is not well known.Methods and ResultsTwenty-five patients with an acute myocardial infarction underwent 99mTc-labeled tetrofosmin (99mTc-tetrofosmin) gated SPECT and cine magnetic resonance imaging (MRI). Wall motion was assessed in 13 left ventricular segments using a 5-point scoring system ranging from 3 (normal) to-1 (dyskinetic). Exact agreement for wall motion scores between gated SPECT and MRI was excellent (92%, kappa=0.82). Furthermore, correlations between the two techniques were also good for end-diastolic volume (r=0.81, P<.0001), end-systolic volume (r=0.92, P<.0001), and ejection fraction (r=0.93, P<.0001).ConclusionIn patients with a recent myocardial infarction, 99mTc-tetrofosmin gated SPECT provides reliable evaluation of global and regional ventricular function and volumes.

Detection of left anterior descending coronary artery stenosis in patients with left bundle branch block: exercise, adenosine or dobutamine imaging?

OBJECTIVES This study sought to assess the diagnostic value of myocardial perfusion imaging during exercise and pharmacologic stress in patients with left bundle branch block. BACKGROUND Patients with left bundle branch block often have septal perfusion defects during exercise perfusion tomography that mimic defects caused by coronary artery disease. These defects appear to be less frequent during pharmacologic stress using adenosine or dipyridamole. Data are scantly on the value of dobutamine tomography in these patients. METHODS We studied 383 consecutive patients with left bundle branch block referred for perfusion scintigraphy over a 5-year span. Perfusion tomography was performed in conjunction with exercise in 206 patients, adenosine in 127 and dobutamine in 50. Coronary angiography was performed within 1 month of the nuclear study in 77, 50 and 27 patients, respectively. RESULTS Exercise, adenosine and dobutamine tomography had similar sensitivity and specificity for the detection of > 50% stenosis in the left circumflex (74% and 96%; 50% and 100%; 63% and 91%, respectively) and right coronary arteries (96% and 86%; 82% and 91%; 79% and 100%, respectively) and similar sensitivity for left anterior descending coronary artery stenosis (88%, 79% and 100%, respectively). However, the false-positive rate for septal defects was higher by exercise tomography (26 [46%] of 57) than by pharmacologic methods (5 [10%] of 48, p < 0.001), and there was no significant difference between adenosine (4 [11%] of 35) and dobutamine (1 [8%] of 13, p = 0.7). The specificity and predictive value of a positive test response for left anterior descending coronary artery stenosis were 36% and 51% for exercise compared with 81% and 85% for adenosine (p < or = 0.001) and 80% and 90% for dobutamine (p < 0.05), respectively. CONCLUSIONS In patients with left bundle branch block, pharmacologic stress is more specific than exercise tomography in the diagnosis of left anterior descending coronary artery stenosis. Dobutamine and adenosine tomography appear to be equally specific in these patients.

Diagnostic accuracy of stress thallium-201 tomography in patients with left ventricular hypertrophy.

Two hundred patients with echocardiographically proven left ventricular hypertrophy underwent quantitative stress thallium tomography. The overall sensitivity and specificity were high (84% and 82%, respectively).

Clinical and Angiographic Significance of a Normal Thallium-201 Tomographic Study in Patients With a Strongly Positive Exercise Electrocardiogram

Among 23,059 patients who underwent exercise myocardial tomography between 1985 and 1994 at our institution, there were 817 (3.5%) with a strongly positive exercise electrocardiogram and normal myocardial tomograms. Among these, 52 patients had no conditions known to be associated with a false-positive exercise electrocardiogram and no previous coronary revascularization, and underwent coronary angiography. Of the 32 patients with significant coronary stenoses, 50% had 1-vessel disease and only 22% had 3-vessel disease (p < 0.05). Among 55 stenosed arteries, 56% were of moderate severity (50 to 74%), whereas only 9% had subtotal or total occlusion (95 to 100%) (p < 0.001). There was a significant gender difference in the prevalence of significant coronary stenoses (80% in male vs 24% in female patients, p < 0.0001). A strongly positive exercise electrocardiogram coupled with normal exercise myocardial tomograms is a rare clinical finding. In women, this finding is usually associated with normal coronary arteries, whereas in men it often denotes coronary artery disease, usually of mild to moderate degree.